On-Truck DPF Cleaning Chemicals Compared Side by Side
Introduction
Truck downtime is expensive, and nobody likes pulling a diesel particulate filter (DPF) off a truck just to get it cleaned. That’s why the aftermarket has long pushed “on-truck” chemical cleaners—spray it in, let it soak, run the truck, and the filter is supposedly back in action. It sounds simple. But what’s actually in these products? Who makes them? And do they really work? Let’s put the leading brands side by side.
A Short History of On-Truck DPF Chemicals
- OEM beginnings: In 1999–2000, PSA Peugeot Citroën debuted fuel-borne catalysts (Eolys fluid) that lowered soot ignition temps so DPFs could burn soot more easily during regens. This was the first “chemical help” directly in-use.
- 2000s aftermarket: Companies like Liqui Moly, Tunap, Wynn’s, JLM, BG, and Bardahl introduced spray-in cleaners marketed as “no dismantling required.” Each version used the same sensor-bung access and soak-rinse cycle.
- 2020s branding: New entrants such as Carbon-B-Gone repackaged the same process with fresh labels and dealer networks, often claiming they were the first or only company offering it. The record shows otherwise.
How the On-Truck Method Works
No matter the brand, the workflow looks like this:
- Warm engine to operating temp, then shut down.
- Remove a sensor (EGT, O₂, or pressure line) upstream of the DPF.
- Insert a spray probe pointed into the filter.
- Apply the cleaner in pulses (usually 5–10 seconds on, 5–10 seconds off) until the full can or bottle is used.
- Let it soak for 10–20 minutes.
- Apply rinse or purge fluid if required.
- Reinstall sensor and clear codes.
- Idle or drive/regen to finish burning off loosened soot.
The Chemistry
Formulas differ in detail but share the same building blocks:
- Solvents (glycol ethers, petroleum distillates) – loosen tarry hydrocarbons.
- Surfactants – spread fluid through the porous filter walls.
- Alkalinity builders (amines, carbonates) – break down sticky films.
- Chelators (EDTA-type salts) – keep metals from redepositing.
- Catalysts (in OEM FBC fluids like Eolys) – lower soot ignition temperature.
The “magic sauce” is not magic—it’s detergent chemistry designed to help soot burn during the next regen. It doesn’t dissolve or remove the inorganic ash that slowly clogs every filter over its lifetime.
Side-by-Side Comparison of On-Truck DPF Cleaning Chemicals
| Brand/Product | Process & Access | Volume Used | Pros | Cons |
|---|---|---|---|---|
| Liqui Moly | Spray through sensor port, soak, then purge | ~1L cleaner + 1L purge | Professional kit, OEM-style instructions | Needs compressed air, more steps |
| TUNAP | Spray in timed pulses, mandatory rinse, regen | 1 bottle cleaner + 1 bottle rinse | OEM-linked, thorough protocol | Adds time, must use both steps |
| JLM | Spray aerosol through sensor port, regen after | 1 aerosol can | Simple, DIY-friendly | Small volume, limited on heavy soot |
| Wynn's | Spray via sensor bung/pressure tube, soak, regen | 1 bottle/can | Easy, widely available | No dedicated purge step |
| Carbon-B-Gone | Cleaner + neutralizer sprayed via pump, regen | ~500mL each (B + C) | Branded pump/training support | Same method as older brands |
Best For: Quick Guide
- Liqui Moly – Best for professional shops with compressed air setups.
- TUNAP – Best for dealer networks or techs following OEM-style service bulletins.
- JLM – Best for DIY users or light soot loads where convenience matters.
- Wynn’s – Best for quick in-shop applications with widely available fluid.
- Carbon-B-Gone – Best for shops that want branded pumps and marketing support.
The Big Claims vs. The Fine Print
- “We’re the only company who does this.” False. Manuals from Liqui Moly, Tunap, Wynn’s, JLM, and others predate newer entrants.
- “Spray dissolves ash.” Not chemically possible. Ash is mineral—metal oxides and sulfates from oil and additives. Liquids won’t burn or dissolve it.
- “Your DPF will be like new.” Soot may burn off more easily, but accumulated ash still restricts long-term flow.
What About Hydrogen Cleaning?
Hydrogen (HHO) cleaning is a separate lane. Instead of spraying chemicals into the DPF, it feeds hydrogen + oxygen gas into the intake while the truck idles. The idea is that hotter combustion helps oxidize carbon. Several companies offer it. Like chemical sprays, it may help with soft soot but cannot remove inorganic ash.
So Which One Is Best?
Stack them side by side and you see the truth: Liqui Moly, Tunap, Wynn’s, JLM, Carbon-B-Gone—they’re all variations on the same recipe. Solvent, surfactant, alkalinity, rinse, regen. The differences are bottle size, branding, and whether a purge is mandatory.
Used properly, these products can buy time. They can bring down soot load enough to get a truck through a regen or keep a filter flowing a little longer. For fleets that need a stopgap on the road, that has value.
But if you’re thinking long-term—really resetting a filter’s capacity—the story changes. The only way to deal with the mineral ash that slowly chokes every DPF is a controlled process with measured flow restoration. That ash doesn’t just block flow; over time it sinterizes inside the brick, permanently baking into the substrate. Once that happens, the filter’s efficiency and service life are cut short, and the only option left is replacement.
That’s why major diesel engine manufacturers, including Cummins, do not endorse on-truck chemical cleaning. Their published service guidance points exclusively to off-truck, multi-step cleaning processes that combine controlled thermal regeneration, pneumatic air-knife cleaning, and pure-water aqueous flushing with full drying and flow testing. Taken together, these are the only ways to fully restore a DPF without risking damage, and the only methods recognized to extend filter life instead of shorten it.
It’s the kind of detail you don’t see in a spray-can instruction sheet, but the more you know, the clearer the picture becomes.